Contamination

Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc.[1][2][3]

For other uses, see Contamination (disambiguation).

Nuances of contamination

Within the sciences, the word "contamination" can take on a variety of subtle differences in meaning, whether the contaminant is a solid or a liquid,[3] as well as the variance of environment the contaminant is found to be in.[2] A contaminant may even be more abstract, as in the case of an unwanted energy source that may interfere with a process.[2] The following represent examples of different types of contamination based on these and other variances.

Chemical contamination

In chemistry, the term "contamination" usually describes a single constituent, but in specialized fields the term can also mean chemical mixtures, even up to the level of cellular materials. All chemicals contain some level of impurity. Contamination may be recognized or not and may become an issue if the impure chemical is mixed with other chemicals or mixtures and causes additional chemical reactions. The resulting chemical reactions from the presence of an impurity may at times be beneficial, in which case the label "contaminant" may be replaced with "reactant" or "catalyst." (This may be true even in physical chemistry, where, for example, the introduction of an impurity in an intrinsic semiconductor positively increases conductivity.[4] If the additional reactions are detrimental, other terms are often applied such as "toxin," "poison," or pollutant, depending on the type of molecule involved.[5] Chemical decontamination of substance can be achieved through decomposition, neutralization, and physical processes, though a clear understanding of the underlying chemistry is required.[6]

Environmental contamination

In environmental chemistry, the term "contamination" is in some cases virtually equivalent to pollution, where the main interest is the harm done on a large scale to humans, organisms, or environments. An environmental contaminant may be chemical in nature, though it may also be a biological (pathogenic bacteria, virus, invasive species) or physical (energy) agent.[7] Environmental monitoring is one mechanism available to scientists to catch contamination activities early before they become too detrimental.

Agricultural contamination

Another type of environmental contaminant can be found in the form of genetically modified organisms (GMOs), specifically when they come in contact with organic agriculture. This sort of contamination can result in the decertification of a farm.[8] This sort of contamination can at times be difficult to control, necessitating mechanisms for compensating farmers where there has been contamination by GMOs.[9] A Parliamentary Inquiry in Western Australia considered a range of options for compensating farmers whose farms had been contaminated by GMOs but ultimately settled on recommending no action.[10]

Food, beverage, and pharmaceutical contamination

In food chemistry and medicinal chemistry, the term "contamination" is used to describe harmful intrusions, such as the presence of toxins or pathogens in food or pharmaceutical drugs.[6][11][12][13]

Radioactive contamination

In environments where nuclear safety and radiation protection are required, radioactive contamination is a concern. Radioactive substances can appear on surfaces, or within solids, liquids or gases (including the human body), where their presence is unintended or undesirable, and processes can give rise to their presence in such places.[14][15] Several examples of radioactive contamination include:

Note that the term "radioactive contamination" may have a connotation that is not intended. The term refers only to the presence of radioactivity, and gives no indication itself of the magnitude of the hazard involved. However, radioactivity can be measured as a quantity in a given location or on a surface, or on a unit area of a surface, such as a square meter or centimeter.

Like environmental monitoring, radiation monitoring can be employed to catch contamination activities early before they become too detrimental.

Interplanetary contamination

Interplanetary contamination occurs when a planetary body is biologically contaminated by a space probe or spacecraft, either deliberately or unintentionally. This can work both on arrival to the foreign planetary body and upon return to Earth.[18]

Contaminated evidence

In forensic science, evidence can become contaminated. Contamination of fingerprints, hair, skin, or DNA—from first responders or from sources not related to the ongoing investigation, such as family members or friends of the victim who are not suspects—can lead to wrongful convictions, mistrials, or the dismissal of evidence.[19][20]

Contaminated samples
Contamination on agar plate

In the biological sciences, accidental introduction of "foreign" material can seriously distort the results of experiments where small samples are used. In cases where the contaminant is a living microorganism, it can often multiply and take over the experiment, especially cultures, and render them useless. A similar affect can be seen in geology, geochemistry, and archaeology, where even a few grains of a material can distort results of sophisticated experiments.[21]

References
  1. "contaminate". Merriam-Webster Dictionary. Retrieved 11 April 2019.
  2. Donovan, R.P. (2001). "1. Introduction". In Donovan, R.P. (ed.). Contamination-Free Manufacturing for Semiconductors and Other Precision Products. CRC Press. pp. 1–3. ISBN 9780824703806.
  3. Ramstorp, M. (2008). "2. Contaminants". Introduction to Contamination Control and Cleanroom Technology. John Wiley & Sons. pp. 20–26. ISBN 9783527613137.
  4. Moudgil, H.K. (2014). Textbook of Physical Chemistry. PHI Learning. p. 278. ISBN 9788120350625.
  5. Alters, S. (2000). Biology: Understanding Life. Jones & Bartlett Learning. p. 828. ISBN 9780763708375.
  6. Midcalf, B. (2004). Pharmaceutical Isolators: A Guide to Their Application, Design and Control. Pharmaceutical Press. pp. 88–89. ISBN 9780853695738.
  7. Vallero, D.A. (2010). "6. Fundamentals of Environmental Chemistry". Environmental Contaminants: Assessment and Control. Elsevier. pp. 289–332. ISBN 9780080470351.
  8. Paull, J. (2014). "Editorial: Organic Versus GMO Farming: Contamination, What Contamination?". Journal of Organic Systems. 9 (1): 2–4.
  9. Paull, J. (2018). "Compensation for GMO contamination". International Sustainable Development Research Society Newsletter (3): 8.
  10. Paull, John (2019) Contamination of Farms by Genetically Modified Organisms (GMOs): Options for Compensation, Journal of Organics, 6(1):31-46.
  11. Bohrer, D. (2012). "Preface". Sources of Contamination in Medicinal Products and Medical Devices. John Wiley & Sons. ISBN 9781118449059.
  12. Rose, M. (2014). "Environmental Contaminants". In Dikeman, M.; Devine, C. (eds.). Encyclopedia of Meat Sciences. 1 (2nd ed.). Elsevier. pp. 497–501. ISBN 9780123847348.
  13. Wilson, C.L., ed. (2008). "Preface: Food—A necessity and a threat". Microbial Food Contamination. CRC Press. pp. xi–xvi. ISBN 9781420008470.
  14. International Atomic Energy Agency (2007). IAEA Safety Glossary: Terminology Used in Nuclear Safety and Radiation Protection, 2007 Edition (PDF). p. 227. ISBN 978-9201007070. Retrieved 11 April 2019.
  15. International Atomic Energy Agency (2010). Programmes and Systems for Source and Environmental Radiation Monitoring, Safety Reporsts Series No. 64. p. 234. ISBN 9789201124098. Retrieved 11 April 2019.
  16. Chatzis, I. (26 July 2017). "Decommissioning and Environmental Remediation: IAEA Conference to Start on Monday". International Atomic Energy Agency. Retrieved 11 April 2019.
  17. Stanford Environmental Health and Safety (29 June 2017). "Radiation Protection Guidance for Hospital Staff" (PDF). p. 21. Retrieved 11 April 2019.
  18. Cockell, C.S. (2005). "Planetary protection—A microbial ethics approach". Space Policy. 21 (4): 287–292. Bibcode:2005SpPol..21..287C. doi:10.1016/j.spacepol.2005.08.003.
  19. Taupin, J.M. (2013). Introduction to Forensic DNA Evidence for Criminal Justice Professionals. CRC Press. pp. 134–8. ISBN 9781439899090.
  20. Geddes, L. (11 January 2012). "How DNA Contamination Can Affect Court Cases". New Scientist. Retrieved 11 April 2019.
  21. Abzalov, M. (2016). Applied Mining Geology. Springer. p. 387. ISBN 9783319392646.
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